VAT polymerization encompasses a group of 3D printing processes characterized by hardening photosensitive resins according to a pre-specified pattern with UV radiation. The 3D build plate begins submerged in a ‘vat’ of viscous photo-sensitive resin. The resin is then incrementally cured to develop a hard texture to form the desired object layer by layer. Typically, post processing includes further curing of the finished object in order to reinforce the chemical bonds and ensure the integrity of the print.

VAT polymerization encompasses a few different 3D printing methods including stereolithography (SLA), digital light processing (DLP), and masked stereolithography (MSLA) also known as LCD 3D printing.


Stereolithographic Apparatus – or more simply referred to as Stereolithography. SLA, or resin printing – is likely the most well known vat polymerization method. Ultraviolet light is directed – like a pen light – and used to cause chemical monomers to link together to form polymers that make up a form of a 3 dimensional object.

Stereolithography can be used to create prototypes for products in development, medical models, and computer hardware, as well as in many other applications. While stereolithography is fast and can produce almost any design, it can be expensive.

As mentioned, stereolithography works by focusing an ultraviolet (UV) laser on to a vat of photopolymer resin. Guided by CAD/CAM software and using mirror-like components called galvanometers, the UV laser ‘draws’ a pre-programmed pattern on to the surface of the photopolymer vat. Since photopolymers are sensitive to ultraviolet light, the resin is photochemically solidified to form a single layer of the desired 3D pattern. The build platform then adjusts and a movable blade recoats the top of the tank with resin, the laser ‘draws’ the next layer which bonds to the previous layer.  The process is repeated for each layer of the design until the 3D object is complete.

Completed parts must then be given a solvent bath to clean away excess and unused resin, and often times require further curing to ensure the integrity of the printed object and the characteristics of the material.


Like SLA, Digital Light Processing is also a form of resin printing but with some key differences.

DLP makes use of a specially designed Digital Light Projector Screen. The projector has the capacity to ‘flash’ (almost like a camera) an entire layer at a time, making the process much faster than SLA. Up until recently, the trade off between SLA and DLP has been speed for quality. Since the DLP is a digital technology, the 2D image that is projected is composed of pixels. When translated into three dimensions, they become voxels. Think of miniscule Lego blocks.

However advances in software and in the DLP technology generally have resulted in prints that are almost indistinguishable from SLA prints and thus presents manufacturers with a unique tool to add to their production process.


Vat polymerization makes use of viscous resins rather than filaments.

While the breadth of 3D printable resins is not as broad when compared to FDM filaments, it is growing with new resins being researched and developed to suit specific requirements. And once developed, they are able to achieve their goals with superior results. And when combined with increased speed and capacity of commercial grade vat polymerization methods like SLA, they provide an incredibly potent manufacturing tools.

EPLUS3D and DSM Somos achieved considerable success and acclaim in their resins, and we have shortlisted a number of them below.

Click on any of the pictures below for resin specific information.

i3D offers each of the resins shown. For more information, please visit our store.


Eplus3D is at the forefront of industrial SLA printer technology, combining large vat size with numerous innovations such as the VarioBeam to enhance not only resolution but the overall production speed.

The SLA A-350/450/650 line of printers is a robust, ergonomically and aesthetically attractive line of printers designed to offer users the optimal combination of ease of use, low maintenance, and high speed and precision.

precise and efficient

  • the patented VarioBeam technology makes use of a wide beam UV laser that varies the spot size to suit the resolution of the print.
    • in practical terms, the VarioBeam can increase print speed by up to 100% without sacrificing print quality
  • each printer incorporates a refined high precision resin level control with a +/- 0.01 tolerance, resulting in a better surface finish
  • each printer also incorporates a dense marble build platform to enhance build precision, durability, and ease of print removal
  • EP-Resin, Eplus3D’s SLA printer control software is designed to streamline and ease production to the point of being a ‘one-click print’

open source

  • any resin with a 355 nm rating can be used in the EPLUS3D SLA A-line of printers, representing a wide range of mechanical properties such as:
    • polypropylene-like and flexible – Somos 9120 or Zortrax Resin Flexible
    • ABS-like – Somos GP 14122 or Accura ABS Black
    • high temperature applications – Somos PerFORM
    • investment casting – Somos ELEMENT
    • …and more
  • EP-Resin control software allows use of 3rd party .stl processing software like NETFABB and Materialize Magics

A350 (click picture for more information)

A450 (click picture for more information)

A650 (click picture for more information)

A800 (click picture for more information)

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